Field
This invention relates to an apparatus for transporting a rotor such as, for example a propshaft. In particular, but not exclusively, the invention relates to an apparatus for transporting a rotor from a first location and loading the rotor into a balancing machine at a second location so that a balancing operation can be undertaken on the rotor. The invention also relates to a method of loading a rotor into such a balancing machine.
Description of the Related Art
Propshafts, and more generally rotors, can be formed of a single rotor portion or multiple rotor portions linked together in end-to-end alignment. Rotors formed of multiple rotor portions may comprise two or three such portions, and less commonly may comprise four portions. The rotor portions are often connected to each other in an articulated fashion, and often adjacent rotor portions can “plunge” relative to each (e.g. they can move axially relative to each other) and the articulate joints can sometimes plunge.
Balancing is typically carried out on rotors to overcome or lessen the problem of ‘unbalance’—the uneven distribution of mass around the axis of rotation of the rotor. Unbalance is when the inertia axis of the rotor is offset from its central axis of rotation, which results from the mass of the rotor not being distributed uniformly about its central axis. Rotors suffering unbalance may generate a moment when rotating which leads to vibration.
It is known to balance a single piece rotor using two balance planes. Each balance plane is a plane disposed substantially perpendicular to the axis of the rotor. When balancing a multiple piece rotor, balancing is carried out in additional balance planes: a two piece rotor may be balanced in three planes, a three piece rotor may be balanced in four planes, and a four piece rotor may be balanced in five planes.
Correction for unbalance is typically carried out by welding balance weights to the rotor. Rotors are designed with zones where balance weights can be added corresponding to the number of balancing planes, which are usually near the end of each rotor portion.
The mechanism for correcting unbalance is typically automated, by which balance weights are attached (e.g. welded) to the rotor at a set position along the axis of the rotor for each plane, within specified balance zones. Once weights for all planes (where required) are applied to the rotor, the rotor unbalance is measured again using the same method. If the unbalance measured in any plane remains outside of a predefined tolerance threshold, a second step of correction is carried out within the corresponding balance zone.
To perform the balancing process a rotor is loaded into a balancing machine that includes an apparatus for driving the rotor. Each end of the rotor is located in a respective mounting apparatus that includes a chuck to secure that end of the rotor. The mounting apparatuses are driven by a drive mechanism so as to transfer torque to the rotor. The ends of the rotor typically include means for connecting the rotor to other components (in its end use), and those endmost connections are often articulated to the remaining component parts of the rotor. The endmost articulated connections often include an array of apertures (e.g. evenly spaced angularly around an axis of the rotor) through which fasteners pass when the rotor is installed in its end use. Due to the manufacturing process of such rotors, it is often the case that the apertures in the endmost articulated connection at one end of the rotor are not aligned with the apertures in the endmost connection at the opposite end of the rotor.
Currently the loading of the rotor into the balancing machine is a manual process. This means that when the rotor is loaded into a balancing machine it is necessary to align the apertures in the endmost connections with the respective mounting apparatus (which usually include one or more projections which are received in the apertures so as to provide a rotationally fast connection therebetween). This manual loading represents a significant time delay between balancing multiple rotors, which has significant cost implications for large-scale balancing, e.g. for the automotive industry.